Meningitis and septicaemia (blood poisoning) caused by the bacterium Neisseria meningitidis (meningococcus) remain important causes of death and disability amongst children and younger adults in the UK and elsewhere. The bacteria can be carried on the mucous membranes in the back of the nose and mouth without causing any symptoms. This so-called carriage state is found in around 10% of the population of the UK at any one time. The bacteria are spread through person to person contact and only occasionally does this spread lead to the development of meningitis and septicaemia rather than carriage. The reasons behind this are not clearly understood. A vaccine against meningococcus group C (Men C), one of five groups of the bacteria that can cause disease, was introduced into the UK in 1999 and led to a sharp drop in the rates of meningitis and septicaemia. The vaccine also led to a decrease in the rates of carriage of the bacteria. This suggests that the vaccine not only generates immune protection preventing meningitis and septicaemia but also generates immunity in the back of the nose and mouth preventing carriage. The way the vaccine generates this “mucosal immunity” is not known and is the topic of our research. This study is the first part of a research programme and aims to identify the way the vaccine works in the blood.

Meningitis and septicaemia (blood poisoning) caused by Neisseria meningitidis (meningococcus) remain important causes of death and disability amongst children and younger adults in the UK and elsewhere. The bacteria can also be carried, without causing symptoms, on the mucous membranes in the back of the nose and mouth. This so-called “carriage state” is found in around 10% of the population of the UK at any one time. The bacteria is spread through person to person contact and only occasionally does this spread lead to the development of meningitis and septicaemia rather than carriage. The reasons behind this are not clearly understood. A vaccine against group C meningococcus (Men C), one of five groups of the bacteria that can cause disease, was introduced into the UK in 1999 and led to a sharp drop in the rates of meningitis and septicaemia. The vaccine also led to a decrease in the number of people carrying the bacteria in the back of the mouth and nose. This suggests that the vaccine not only generates immunity preventing meningitis and septicaemia, but also generates immune protection in the back of the nose and mouth, preventing the carriage state. This prevention of carriage may be central to the way the vaccine works, as it stops the bacteria circulating from person to person and therefore stops its spread within the population as a whole. The way the vaccine generates this protection in the back of the nose is not known. We hope that this research will help us to better understand this important question. We are using a vaccine of the same type as the Men C vaccine already widely used in the UK. However, instead of covering just one group of meningococcus (group C), the vaccine we are using covers four of the five groups of meningococcus that are known to cause disease (groups A, C, W135 and Y). The vaccine is manufactured and provided to us by Novartis Vaccines, a commercial vaccine manufacturer. It is not yet licensed for use and other studies using the vaccine are ongoing in Europe and in Latin America. We will be comparing the immune response generated by the vaccine in the tonsils (at the back of the nose and mouth) to that occurring in the blood.